Process for reducing shrinkage and improving crease retention of wool-synthetic fiber blends

ABSTRACT

Permanent crease properties are given to wool-synthetic fiber blends, such as wool-orlon blends, and to wool alone. The process is slightly different in the two cases, wool-synthetic blends being treated by chlorinating and oxidizing agents under acid pH&#39;&#39;s. After washing and drying, creases in garments are restored. In the case of wool only, the same chlorination and/or oxidation treatment is used and then in a separate step, after removing the chlorination-oxidation residue, treated with synthetic resin finish, which is then cured. In both cases the treatment with the chlorination-oxidation agent is under acid conditions.

United States Patent [191 Moore et al.

[ 51 May 13,1975

[75] Inventors: Clyde T. Moore, Bennettsville;

Harry L. Mercer, Cheraw, both of SC.

[73] Assignee: J. P. Stevens & Co. Inc., New York,

[22] Filed: June 28, 1972 [21] Appl. No.: 266,850

[52] US Cl 8/l15.7; 8/128 R; 8/128 A [51] Int. Cl D06m 9/00 [58] Field of Search; ..8/115.7,128 R, 128 A [56] References Cited UNITED STATES PATENTS 2,516,055 7/1950 Haigh et a1 8/128 R X 2,671,006 3/1954 McLauchlan 8/128 R 3,480,383 11/1969 Krasny et a1. 8/128 R 3,521,997 7/1970 Barber et al.. 8/128 R X 3,628,909 12/1971 Goldberg et a1. 8/128 R X 3,676,057 7/1972 Brown 8/128 A 3,706,528 12/1972 Dobinson et al 8/128 A FOREIGN PATENTS OR APPLICATIONS 1,074,731 7/1967 United Kingdom 8/128 A 8/1957 United Kingdom 8/128 R 6/1949 Australia 8/128 A OTHER PUBLICATIONS Wool lts Chemistry and Physics, Alexander, Peter et 211., page 176, 1954.

Primary Examiner-Thomas J. Herbert, Jr. Attorney, Agent, or Firm-Robert Ames Norton, Esq.; Michael T. Primer, Esq.; Saul Leitner, Esq.

[57] ABSTRACT Permanent crease properties are given to woolsynthetic fiber blends, such as wool-orlon blends, and to wool alone. The process is slightly different in the two cases, wool-synthetic blends being treated by chlorinating and oxidizing agents under acid pHs. After washing and drying, creases in garments are restored. In the case of wool only, the same chlorination and/or oxidation treatment is used and then in a separate step, after removing the chlorination-oxidation residue, treated with synthetic resin finish, which is then cured. In both cases the treatment with the chlorination-oxidation agent is under acid conditions.

6 Claims, No Drawings 1 PROCESS FOR REDUCING SHRINKAGE AND IMPROVING CREASE RETENTION OF WOOL-SYNTHETIC FIBER BLENDS BACKGROUND OF THE INVENTION Wash resistant, crease-proofed garments, often re ferred to in the art by the term permanent press garments, usually comprise synthetic fibers or blends of synthetic fibers with cellulosic fibers, such as cotton, viscose rayon, etc. The permanent press treatment is with a synthetic resin dispersion which is then cured after the garment is made and the creases ironed in and produces a crease-proof or crease-resistant finish.

Wool or wool blends present problems of crease retention in garments made from the fabric which will withstand ordinary washing under the fairly mild conditions usually recommended for wool textiles. The problem has not been completely successfully solved. The attempt to make wool or wool blends into fabrics in which creases are better retained involves treatment with a synthetic resin dispersion and curing the resin when the creases of the garment are ironed in. The amount of synthetic resin required, however, is fairly high because of the nature of the wool, and this large amount of synthetic resin has often produced a finish which is harsh and so adversely affected the hand of the fabric. Thus while the fabrics after ironing in creases have improved crease retention, there is still room for further improvement, and it is with such further improvement with wool textiles and those made from wool-synthetic fiber blends, such as wool-acrylonitrile fibers, wool-polyglycol terephthalate fibers and the like, that the present invention deals.

It has been proposed to treat woolen textiles or yarns with chlorinating and oxidizing agents, usually the same agent which has both chlorinating and oxidizing properties. The result has been to open up the surface scales of the wool fibers, and this has produced markedly improved shrink resistance on washing. Throughout the present specification we will refer to such treatments as chlorination treatments, it being realized that the reagents both chlorinate and oxidize. Marked reduction in shrinkage of wool textiles under washing has been achieved, and the shrink-proofing, as this operation is referred to in the art, has been successful and the shrink-proofing treatment has been used for many years with woolen textiles. However, the chlorination, while it greatly improves shrinkage, makes crease retention worse. The opening up of the scales of the wool fiber by the chlorination treatment causes the fibers to absorb water much more readily. This is advantageous in dyeing, and of course when the material dries it has greatly improved the shrink resistance; however, the wool which has absorbed water so readily is quite limp and creases in garments disappear or are adversely affected on washing to a greater degree than if the wool had not been chlorinated. It should be realized that the properties of the shrink-proofing or shrink resistance and crease retention are not the same property, and, as has been pointed out above, treatments which enhance one often make the other problem worse.

In order to attempt to obtain reasonable crease retention it has been proposed to chlorinate wool at alkaline pHs and then treat with a resin finish, such as an aminoplast. It has also been proposed to chlorinate wool under acidic condition in a bath in which synthetic resin is incorporated. The chlorination and resin treatment occur at the same time in which is effectively a single step or single stage. Some improvement in crease retention results, but there are serious drawbacks. Many resins, such as aminoplasts, for example melamine formaldehyde resin, react with the chlorinating agent, and as a result amounts of resin and/or chlorinating agent have to be rather markedly increased, with a corresponding significant undesirable increase in cost. The charge on the wool in the acid bath also results in attracting particulate matter in the bath, which is often colored and which can cause spots on the wool.

It has also been proposed to improve crease retention of synthetic fibers or even wool-synthetic fiber blends by means of the same type of resin finish. This requires additional reagents and increases cost.

SUMMARY OF THE INVENTION In the present invention there are two variants. In each variant wool or wool-synthetic fiber blend is treated with a chlorinating agent under acidic conditions. The treatment may be of yarns or fabric produced therefrom. In the case of blends, this is usually all that is needed because the synthetic fibers have a memory. In other words, when they have been creased with a sufficient application of heat, the synthetic fibers tend to return to their original shape after washing. With blends, the wool tends to make the memory recovery less effective. However, in the above described variant of the present invention the blend is first chlorinated under acid condition, and often this is all that is needed.

In the case of all wool fabric, chlorination opens up the wool fiber structure and facilitates absorption of water on washing. From the standpoint of crease retention, this is exactly the wrong thing to do with all wool fabric as crease retention becomes even less than in wool fabrics which have not been chlorinated. In the case of wool-synthetic fiber blends, however, surprisingly, the chlorination treatment under acidic conditions improves the crease retention resulting from the memory of the synthetic fiber. That a treatment of the wool blend which would render an all wool fabric far worse, as far as crease retention is concerned, should greatly improve crease retention in a blend is unexpected and unobvious. It is not desired to limit the present invention to any particular theory of action. How ever, we believe that the opening up and swelling of the wool renders it more pliable and limper when wet. The hydrophobic character of the synthetic fibers causes them to dry much more rapidly after washing in water than the chlorinated wool and the crease returns because of the memory and is not hampered by any stiffness of the wool, which is still wet and very limp. This explanation of the surprising results of the present invention seems to have a good deal of plausibility once it is known that the greatly improved crease retention is attained. However, it is possible that other factors may be involved and even possible that they may be more important factors. Accordingly, the invention is not limited to any theory of action. All that we know is that crease retention in the blend is markedly improved by chlorination of the wool fibers in the blend.

The second variant of the present invention involves all wool or substantially all wool fabrics. Chlorination alone will not improve crease retention, as has been pointed out above. In this variant the difference from the prior art lies in first chlorinating the wool and then,

after the chlorination is complete, removing all of the residue of chlorination and oxidation materials. Only then is the wool treated with a synthetic resin dispersion under the usual conditions, but much less synthetic resin is required and so does not produce a harsh hand. The synthetic resin may be any of the well known types, such as aminoplasts.

It should be noted that in this second variant of the invention the chlorination must be under acid pHs and not the standard alkaline pHs which are most commonly used in chlorination of wool. In other words, this variant is a very rigidly restricted and quite narrow one, requiring first chlorinating the wool, not under any conditions but only under acid conditions, removing all of the chlorination-oxidation residues, and then treating the wool with the resin. This is a two-step operation or, strictly speaking, a three-step operation if one considers the washing out of the chlorinating agents as a separate step, instead of a single step or bath operation. The material does not attract undesirable particulate matter and spots are completely eliminated, which is one of the serious problems with the one-bath process in which wool chlorination and resin finish application are effected in the same bath. Needless to say, in the present invention minimum amounts of chlorinating agent and resin are used because there is no reaction of chlorinating agent with the resin. Better results are obtained with a significant saving on the amount of reagents required, and of course the elimination of any undesirable reaction products of the chlorinating agents and resin.

Throughout the specification reference will be made to wool as this is the most important proteinaceous fiber. The invention is, however, not limited to fabrics comprising wool, and other proteinaceous fibers, such as mohair, camel's hair, hair from the musk ox or, as it is sometimes called, ovibos, and the like, may take the place of the wool. In every case these proteinaceous fibers have the typical overlapping scale surface which is a characteristic of wool fibers and of course they behave in the same manner. In the claims the broader language will be used, but throughout the remainder of the specification to avoid confusion the description will be in terms of the most common overlapping-scale proteinaceous fibers, namely wool. It is also not necessary in the present invention that wool be the only proteinaceous fiber. Mixtures are, of course, included, such as mixtures of wool fibers and mohair and the like.

The chlorinating agents used in the present invention are those used in the prior art except that there is the strict limitation that the chlorination must be under acid pHs. The present invention does not, therefore, depend for distinction from the prior art on using a particular or special chlorinating agent and the common chlorinating agents, such as hypochlorites, cyanuric chlorides, and the like, may be employed. Also, the amounts used in chlorination do not differ from those used to chlorinate wool to produce the entirely different property of shrink reduction or shrink-proofing. This is a practical operating advantage as it is not necessary to learn new or special wool chlorination techniques. The same considerations hold true when the chlorination is of wool-synthetic fiber blends, but of course in such a blend the chlorination is of the wool only and therefore amounts of chlorinating agent must be based on the wool content. The synthetic fibers used must be those having a memory, which are, for the most part, thermoplastic fibers, such as polyethylene terephthalate, (Dacron), polyacrylonitriles, superpolyamides, and the like. In other words, the invention does not operate because one of the mixture of fibers is a synthetic rather than a natural fiber, for a synthetic cellulosic fiber, such as viscose rayon, is ineffective. The fiber must have a memory after having been heat set.

When the variant for all-wool fabric is used, not only is the first step, chlorination, carried out in conventional manner except that it is essential that the pH be acid but the last step, that is the resin treatment after chlorination and removal of the chlorinating agent, is again effected in conventional manner, that is to say, the resin finish is applied, usually from dispersions, in an uncured or incompletely cured state and is finally cured on the material in the same way as has been done before where such a finish has been applied to various textile materials. In this step also it is not necessary to learn new techniques, which is an operating advantage, just as is the more or less standard chlorination procedure except for the acid pHs.

While it is necessary that the chlorination be effected under acid pHs, the particular pH or pH range used is not that which distinguishes the present invention from the prior art. A very suitable range of pI-Is for the chlorination step or oxidation step is from a pH of 3.5 to a pH of 6.9.

The present invention in either of its variants may be applied to finished fabrics, woven or knitted, or it may be applied to yarn of wool or wool blends. The reference to wool is directed to the chemical nature of the fibers and not to the particular yarn twist; in other words, hard-twisted worsted yarns are considered to be made of wool for the purposes of the present invention. Blends with synthetic thermoplastic fibers are often made in the form of worsted blends, and of course these are included in the general designation of blends having wool fibers.

It has been stated above that blends of wool and a cellulosic fiber, natural or synthetic, are not the blends which are used in one of the variants of the present invention. This is not to say that a blend may not contain a minor portion of cellulosic fibers. So long as they are not such a major portion that they prevent good crease retention by reason of the memory of the synthetic thermoplastic material, they may be present.

In the description of the preferred embodiments which will follow, wool is used as a typical illustration of an overlapping scale protein fabric.

Often wool or wool blends are dyed. In fact, the chlorination, which is the first step in both variants, usually renders the wool more dyeable. The fibers may be treated by the present invention, dyed and formed into fabric or treated by the present invention, formed into fabric and dyed afterwards. It is also possible to apply the present invention to already dyed fibers, as with most dyes there does not appear to be much shade change. However, with certain dyes which are sensitive to chlorine or oxidizing, of course the treatment of the present invention should precede any dyeing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be described in conjunction with a number of typical illustrative examples.

EXAMPLE 1 A 70/30 blend of polyacrylonitrile and wool is formed into yarn and treated with an aqueous solution of 2 weight percent of sodium sulfate at 90 100F. There is then added 95 percent, based on the weight of the wool content, of a conventional wool chlorinating and oxidizing agent such as sodium dichloroisocyanurate, which is sold under the name of Basolon DC. or CDB 63. The pH is then adjusted to 4.5 to 6.0, preferably approximately 5.0. Chlorinationoxidation is effected by heating to 90 100F. for about an hour, finally raising the temperature toward the end of the reaction to 120F. Unreacted chlorine is removed by adding 2 percent of sodium bisulfite, based on the weight of the goods, preferably in the form of an aqueous solution. Heating at 120F. is continued for about 20 minutes and the yarn then washed with water.

After drying, the yarn may be dyed and formed into a fabric, the fabric cut and formed into a garment and pressed. If desired, standard resin finish of 4 percent melamine formaldehyde resin may be applied, and the pressing will result not only in forming a crease but curing the resin.

EXAMPLE 2 The procedure of Example 1 is repeated with allwool fiber. In this case after washing out the chlorine the yarn is dried and a melamine or urea formaldehyde resin finish applied in the conventional manner.

EXAMPLE 3 A 70/30 acrylonitrile homopolymer and wool were chlorinated as described but using as a chlorinating agent dichloroisocyanuric acid. After removing the chlorine, drying and forming a fabric, the fabric was padded with an aqueous formulation having a proportion of 41 pounds stabilizer 63, 5.3 pounds sodium bisulfite, 17% pounds Velvamine ATS modified alkyl amine condensate based on 50 gallons. After padding, the fabric was dried at 30 yards per minute at 210F. Drying took about 3 /2 minutes. Results were as good as in Examples 1 and 2.

EXAMPLE 4 A blend of 55 percent acrylonitrile homopolymer, 30 percent wool and 15 percent polyethyleneterephthalate was treated as described in Example 3, dyed and made up into slacks, and creases pressed in under 30 pounds air pressure at 310F. The finish applied was an acrylic finish, which was cured for 10 minutes at 300F. The smoothness was retained after five machine washes at F. and tumble drying, and the creases were well retained although the tumble drying is a very severe test.

EXAMPLE 5 All-wool piece goods were treated as described in Example 2, using 2 percent sodium sulfate, 3 percent dichlorocyanuric acid, 1% percent tetrasodium pyrophosphate, (all by weight), adjusting the pH to 4.5 with acetic acid. The chlorination resulted in a top chlorination of the wool. When creased and washed, crease retention was excellent. As chlorination and oxidation slightly decreases the strength of the wool, yarn top chlorinated as above was blended with an equal amount of untreated wool. Wear resistance was increased without significant loss of crease retention.

We claim:

1. A process of treating yarns and fabrics produced therefrom, the yarns being composed of blends of pro teinaceous fibers having overlapping scales and synthetic thermoplastic fibers having heat settable memory at conventional garment pressing temperatures, in order to reduce shrinkage and improve crease retention on washing, which consists essentially in shrinkproofing said proteinaceous fibers by oxidizing them with an acidic aqueous solution of a chlorinating agent for said proteinaceous fibers, removing the acidic aqueous solution, subjecting a fabric composed of said yarns to creasing by pressing in creases in a conventional garmerit press under conventional garment pressing conditions, whereby said fabrics exhibit increased crease retention on washing and drying.

2. A process according to claim 1 in which the proteinaceous fiber is W00].

3. A process according to claim 2 in which the synthetic thermoplastic fiber comprises polyacrylonitrile.

4. A process according to claim 1 in which the pH is between 4.5 and 6.0.

5. A process according to claim 4 in which the proteinaceous fiber is W00].

6. A process according to claim 5 in which the synthetic themoplastic fiber comprises polyacrylonitrile. 

1. A PROCESS OF TREATING YARNS AND FABRICS PRODUCED THEREFROM, THE YARNS BEING CO,POSED OF BLANDS OF PROTEINACEOUS FIBERS HAVING OVERLAPPING SCALES AND SYNTHETIC THERMOPLASTIC FIBERS HAVING HEAT SETTABLE MEMORY AT CONVENTIONAL GARMENT PRESSING TEMPERATURES, IN ORDER TO REDUCE SHRINKAGE AND IM06PROVE CREASE RETENTION ON WASHING, WHICH CONSISTS ESSENTIALLY IN SHRINK-PROOFING SAID PROTEINACEOUS FIBERS BH OXIDIZING THEM WITH AN ACIDIC AQUEOUS SOLUTION OF A CHLORINTING AGENT FOR SAID PROTEINACEOUS FIBERS, REMOVING THE ACIDIC AQUEOUS SOLUTION, SUBJECTING A FABRIC COMPISED OF SAID YARNS TO CREASING BY PRESSING IN CREASES IN A CONVENTIONAL GARMENT PRESS UNDER CONVERNTIONAL GARMENT PRESSING CONDITIONS, WHEREBY SAID FABRICS EXHIBIT INCREASED CREASE RETENTION ON WASHING AND DRYING.
 2. A process according to claim 1 in which the proteinaceous fiber is wool.
 3. A process according to claim 2 in which the synthetic thermoplastic fiber comprises polyacrylonitrile.
 4. A process according to claim 1 in which the pH is between 4.5 and 6.0.
 5. A Process according to claim 4 in which the proteinaceous fiber is wool.
 6. A process according to claim 5 in which the synthetic themoplastic fiber comprises polyacrylonitrile. 